A liquid crystal display device utilizing the electro-optical effects of liquid crystals or an organic electroluminescence display device using an organic electroluminescence element are being developed as display devices to be used in electric appliances or electronic devices. These display devices are formed with a display screen using a plurality of pixels arranged above a substrate. A liquid crystal element or an organic electroluminescence element is arranged as a display element in each pixel of the display device. The display device displays video or still images by driving a pixel part arranged with such pixels using a pixel circuit and driving circuit formed by a transistor. The display device includes a terminal part which is applied with a video signal, a timing signal for controlling the operation of a circuit, and power and the like.
The display device is stacked with an insulation film, semiconductor film and conductive film, and by forming these thin films into a certain shape, a wiring pattern for forming a transistor or a circuit is created. In this case, each terminal electrode in the terminal part is required to be exposed to the exterior of the display device. As a result, in order to make the terminal part, different processing is required for a transistor or display element arranged in a pixel part. Specifically, a process for exposing the surface of each terminal electrode in the terminal part to an exterior surface is required.
For example, in the manufacturing process of a display device in Japanese Laid Open Patent Publication No. 2004-165068, a method is disclosed in which an organic insulation layer which functions as a laser removal layer is arranged above a terminal part, and after forming a passivation film covering the entire surface of a substrate, laser light is irradiated onto the organic insulation layer of the terminal part covered with the passivation film to generate ablation in the organic insulation layer and expose a terminal electrode in a terminal region.
However, since processing control in a depth direction is difficult in a method for exposing a terminal electrode by irradiating laser light, when attempting to securely expose a terminal electrode, the surface of the terminal electrode becomes damaged by the laser light. On the other hand, processing is complex in a method for exposing a terminal electrode by etching and there are problems of a drop in yield and an increase in manufacturing costs. For example, in a terminal part of a display device, since a plurality of cover films with different materials are deposited in a manufacturing process, an etching method for each layer is required or it is necessary to change an etching liquid or etching gas, and further manufacturing equipment for exposing a terminal electrode is required.